Process for the preparation of alkyl phenyl phosphoric acids and the salts thereof



Patented Got. 20, 1953 PROCESS FOR THE PREPARATION OF ALKYL PHENYL PHOSPHORIC ACIDS AND THE SALTS THEREOF Harry R. Gamrath, St. Louis, Mo., assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application May 1, 1950, Serial No. 159,374

This invention relates to alkyl phenyl phosphoric acids and the salts thereof; more specifically, this invention relates to an improved process for the preparation of certain alkyl phenyl phosphoric acids having the formula wherein R1 represents an alkyl radical terminating with a CH2 group and containing from 6 to 18 carbon atoms and R2 represents a phenyl radical. The novel process of this invention is also applicable for the salts of the above described alkyl phenyl phosphoric acids. It is an object of this invention to provide an improved commercially feasible process for the preparation of the above described alkyl phosphoric acids. Further objects will become apparent from the description of the novel process of this invention.

When one mol of an alkyl phosphoryl dichloride is added to an aqueous alkaline solution containing one mol of an alkali metal arylate, at least three possible reactions can take place. The phosphoryl derivative may hydrolyze to form the alkyl phosphoric acid, the phosphoryl derivative may react to give a mixture consisting of neutral alkyl diaryl phosphate and alkyl phosphoric acid or the alkyl phosphoryl dichloride may react to give alkyl aryl phosphoric acid. When the yield of alkyl aryl phosphoric acid is over 50% based upon the alkyl phosphoryl dichloride, then the reaction to produce this compound is the predominating of the three mentioned.

In a process for the preparation of alkyl phenyl phosphoric acids by the reaction of an alkyl phosphoryl dichloride with an alkali metal arylate in an aqueous alkaline solution, it was discovered that in the series where the alkyl group in the alkyl phosphoryl dichloride varies from methyl to octadecyl, the nature of the reaction is quite different when alkyl phosphoryl dichlorides wherein the alkyl substituent contains from 1 to 5 carbon atoms are utilized than when alkyl phosphoryl dichlorides wherein the alkyl substituent contains from 6 to 18 carbon atoms are utilized. When C1 to C5 alkyl phosphoryl dichlorides are utilized in such a reaction, the principal reaction 11 Claims. (01. 260-461) 2 Yields obtained from one mol of alkyl phosphoryl dichloride and one mol sodium arylate Percent Yield of Alkyl Phosphoryl Dichloride Alkyl Aryl Phosphoric Acid Ethyl phosphoryl dichloride. 29. 2 Butyl phosphoryl dichloride 46. 0 n Hexyl phosphoryl dichlorid 50. 9 2-Ethy1hexyl phosphoryl dich1oride 80. 1 n-Decyl phosphoryl dichloride 89. 1 Octadecyl phosphoryl dichloride 67. 9

A preferred embodiment of this invention, therefore, consists in reacting a one molecular proportion of an alkyl phosphoryl dichloride wherein the alkyl substituent is an alkyl radical terminating with a CH2 group and containing from 6 to 18 carbon atoms, with approximately a one molecular proportion of an alkali metal phenolate dissolved in an aqueous alkaline solution. After the reaction is complete, the alkyl phenyl phosphoric acid or its salt may be recovered from the reaction mixture by any method well known to those skilled in the art for the recovery of such type of phosphoric acids.

The following examples are illustrative of the novel process of this invention:

, EXAMPLE I n-Heryl phenyl phosphoric acid Into a glass reactor was charged 94.1 g. of phenol, 1,000 cc. of water and 80.0 g. of sodium hydroxide. The aqueous sodium hydroxide solution was added slowly to the phenol-water mixture, keeping the reaction temperature below 25 C. Then the sodium phenate solution was cooled to about 15 C. and 218.6 g. of n-hexyl phosphoryl dichloride (obtained from one mol of POCls) was added during about 5 minutes, the reaction temperature being 16-22 C. The reaction mass was then stirred for an additional 12 hours at approximately 25 C. adding sodium hydroxide solution to keep the mass alkaline to phenolphthalein. About 181 g. of 50% sodium hydroxide solution was added during the stirring period.

After completing the reaction, the reaction mass was allowed to settle and the aqueous layer was separated from the neutral ester. The aqueous layer contained the sodium salt of n-hexyl chloric acid to liberate the n-hexyl phenyl phosof 50.9% based on P0013. It had the iollowing"- physical properties: r..

Sp. gr. at 25l25 C 1.1245 Assay "re-Per s n 96-9 Analysis lfiit iifii Calculated for GIZHIQOAP 1 Found 13 Z-ethylhemyl phenyl phosphoric acid 271E531, round-bottom, l'IhFCQ-nBQkGd flask wasrcharged with 188.2 g. of phenol and 1120 cc. of water. 160 g. of a 50% sodium hydroxide sol ition wa then slowly added up t e mixture of phenol and water at-such arate'and withtchstjant cooling .toIrnaintain a. reaction. tempera.-

titre below :25 C; To the cooledsandconstantly stirred sodium phenalte solution was thenadded 494.4 g. of -2-ethylhexyl phosphoryl dichloride icb a n s al wo 1 9. of P 3) over a period oflabout' one hour, keeping the temperature of The alkaline auces-sla er c nt nin he 9- dium z-ethylhexyl phenyl phosphate was separated from the neutral-ester and extracted several times. withben zeneat 30-40? C The benzene extracts were washed with'a 1% sodium hydroxide solution-andwith'water, and the washin'gs were combined-with the: aqueous 1 alkaline solution. After extraction; the aqueous alkaline solution was acidified with 78% sulfuric acid to liberate the 2-ethylhexyl phenyl phosphoric acid. The 2-e'thylhexyl'phenyl 'phosphoric acid waswashed several times with water and then steamed at 100 to 105*"0. to remove the benzene.

Theoil was washedo'nee' more with water and then dried by heating under reduced pressure. 372.'1-g. of 2-ethylhexyl phenyl phosphoric acid was recovered, representing' a--'yield of 652% based on POCh, which hadthe following propt L Sp. gr. at 25/25 C 1.0906

' Phosphorus, t percent Calculated f0! 0 4112304]? 10. 8 l 'T?': 'I'f':f

4 EXAMPLE III Z-ethylheryl cresyl phosphoric acid The sodium cresylate used in the preparation of Z-ethylheXyI bresyl phosphoric acidwas made by charging a 5-l-iter flask with 486.5 g. of cresol (mainly a mixture of metaand para-cresol, but also containing a small amount of orthogresol-and nylenols), 2,500 cc. of water and 360 g. of 50% sodiung -hydroxide. After cooling the stirreds'odium cresylate to about 10 C., 1,099.4 g. of 2-ethylhexyl phosphoryl dichloride (obtained nl nuteperibdjtrie' reaction temperature being maintained at'810 C. during this period. The

reactionmixture was then warmed to about 55 C. --in-approximately one hour and sodium hydroxide solution added to keep the mass alkaline to phenolphthalein, and then stirring was continued for two hours more with the mass temperature inthe'r'ange of 555-? C. The reaction'mass was then allowed to c'ooland settle whereupon it separatedintotwo-layers. r The aqueous 'layerwas separated from the neutral ester-andacidified liberating an oil which was separated therefrom. The oil was steamed to remove dissolved cresol. After steaming, the oil was again-dissolved in dilute sodium hydroxide solution and the solution extracted with benzene to remove any residual neutral esters. The aqueous alkaline solution was then acidified to liberate Z-ethylhexyl cresyl phosphoric acid which was separated and-steamed to remove any-dissolved benzene. The g-ethylhexyl cresy p sp ric acid as as ed e r l times with water at 60-65 C.- and themass dried by heating under reduced pressure. 1080.8 g. of- 2,-ethylhexyl-cresyl phosphoric acid were obtained representing a. yield of 80.1% based on POCh. The 2-ethylhexyl cresyl phosphoric acid thus obtained had the following properties;

Sp. gr. 25 /2 5 C 1.0814

Phosphorus,

Analysls percent Calculated for Cis'HrsChP ta/ m I n-Decyl crest Z phosphoric acid In accordance with the procedure described in Example III, nedecyl-cresyl phosphoric acidwas prepared utilizing the following reactants:

In this case the sodium salt ofn-decyl cresyl phosphoric acid was insoluble in the reaction mass. To facilitate the filtration operation}- the somewhat sticky mass was mixed with an inert material and then 'thecomp'ound was liberated in an aqueous mediun 1 byacidification. The liquid n-decyl cresyl-pho'sphoric acid was refined as usual. a

From the charges listed above, 292.? g. of n-decyl cresyl phosphoric acid were obtained representing a yield'of 89.1% based on n-decyl phosphoryl dichloride. The n-decyl cresyl phosphoric acid thus obtained had the following properties:

Octadecyl phenyl phosphoric acid The octadecyl radical in the octadecyl phosphoryl dichloride utilized in this example was derived from 2-(l,3,3-trimethyl buty1)-5,'7,7-trimethyloctanol. I

383.3 g. of octadecyl phosphoryl dichloride (obtained from one mol P0013) were added to an aqueous solution of sodium phenate made from 94.0 g. of phenol, 1800 cc. of water and 80.0 g. of 50% sodium hydroxide. All of the octadecyl phosphoryl dichloride was added to the sodium phenate solution over a 35 minute period with the reaction temperature maintained at about 10 C. To complete the reaction, the mass was stirred an additional 5% hours allowing the mass temperature to increase to about 40 C. During the stirring period, sodium hydroxide solution was added to keep the mass alkaline to phenolphthalein.

After the reaction was complete, the mass was allowed to stand whereupon solid sodium octadecyl phenyl phosphate separated. The solid sodium salt was separated by decantation and washed with water. The sodium octadecyl phenyl phosphate was then acidified with hydrochloric acid to liberate the very viscous octadecyl phenyl phosphoric acid. After washing with water, octadecyl phenyl phosphoric acid was dried by heating under reduced pressure. 289.3 g., representing a yield of 67.9% based on P0013, of octadecyl phenyl phosphoric acid was obtained having the following analysis:

Phosphorus Analysis pewent Calculated for CiiHiQOi 7. 3 Found 7. 7

EXAMPLE VI Nonyl ortho-chlorophenyl phosphoric acid In accordance with the procedure described in Example III, nonyl ortho-chlorophenyl phosphoric acid was prepared utilizing the following An excellent yield of substantially pure nonyl ortho-chlorophenyl phosphoric acid was thus obtained.

EXAMPLE VII Tetradecyl 4-chZoro-2-methylphenyl phosphoric acid In accordancewith the procedure described in a Example 111, tetradecyl 4, -chloro-2'-methylphenyl phosphoric acid was prepared utilizing the fol-1 lowing reactants:

Tetradecyl phosphoryl dichloride (the tetradecyl radical was derived from a branched chain tetradecyl alcohol derived from the polymerization of olefins) 165.5 Para-chloro-ortho-cresol 71.3 Water 1000 Potassium hydroxide (for potassium pchloro-o-cresylate) 28.1

An excellent yield of substantially pure tetra decyl 4-chloro-2-methylphenyl phosphoric acid was obtained.

EICANEPLE VIII Z-methylpentyl o-nitrophenyl phosphoric acid ants Parts by weight; 219' o-Nitrophenol .139

2-methy1pentyl phosphoryl dichloride Water Sodium hydroxide (for sodium o-nitrophenate) EXAMPLE Ix Z-ethylhexyl 2,4,5-tribromophenyl phosphoric acid In accordance with the procedure described in Example III, an excellent yield of substantially pure Z-ethylhexyl 2,4,5-tribromophenyl phosphoric acid was obtained utilizing the following reactants:

Parts by weight 2-ethylhexyl phosphoryl dichloride 61.8 2,4,5-tribromophenol 83 Water 500 Sodium hydroxide (sodium 2,4,5-tribromo phenate) In addition to the alkyl phenyl phosphoric acids prepared in the preceding examples; the following alkyl phenyl phosphoric acids or the salts thereof are further illustrations, but not limitative, of alkyl phenyl phosphoric acids which may be prepared in accordance with the novel process of this invention:

n-Hexyl cresyl phosphoric acid 2-ethylbutyl o-chlorophenyl phosphoric acid Heptyl 2,4-dibromophenyl phosphoric acid n-Octyl 4-bromo-2-methylphenyl phosphoric acid Trimethylhexyl 3,5 dimethylphenyl phosphoric acid - Decyl o-ethoxyphenyl phosphoric acid Y Parts by weight In the above list of compounds the nonyl and: Idodecyl radicals maybe derived," in'additioriio.

nde idfhxdr irees s oern; er am raetnes wchainalliyl, a! T us.

nonyl coho m b -smeared. ea-P ea i ion $.1 lene. tqi rma, we s-W. a thenhe sae edi with ar en. monoxide an n fl a to erm; hrae hsdpha n r ma ex alcohol? Nonaldehyde may be prepared; inf a similar manner and may then be subjected to an aldol condensation to form -a branched chain primary octadecylalcohol The alkyl radicals may also be ;derived from: straight'chain primary obta'nedbythe hydrogenation oljcoc'o- In tHecompoundsof the invention, includingthosedisclosedabovethe cresyl radical maybe ortho-cresyl, para-cresyl or meta-cresyl, for exarnplefz -etliyl-hezgyl phenyl ortho cresyl phospliate, Z-ethylheX-yL phenyl para-cresyl P1 9 pirate, or-2- ethylhexyl phenyl meta-cresyl phos piste. Also, the products of the invention'may comprise mixtures of" phosphate esters containifig ortho, para and/or meta-cresylradicals:

While specific quantities, reactants and reaction conditions have been'set forth in the preceding examples; it-:isnottintended that the novel process of this reaction beisolely limited theret west-amiss r atienq. n he e ct nts re es a d: ea t e t auditions he a 'nhq ee l i h e mo als-unnatural? them e pf m +2 C. to about +2 C. and wh' e r I theihydrogen chloride formed until-:the; reaction is substantially complete, and then continuing h I the hydrogen chloride iorrnedfat? temperaturesnot n eiic e ssojf abiout 0;. The hydrogen; chloride niay lee-removed in any convenient manner', such as by blowing air-through the reaction mixture or by running the reac tion under a reduced-pressure Such a, process; for the, r a at on. o a a yl hosphor-r1 tcl chlo-n rides is describedzandmlaimedin my. onendins... application Serial; No-.13.5,1311, filed December, 27;, 1949.;

In; ;the.- reaction-.betweenr the. alkyl phosphoryl dichloride and the alkali metal salt of a phenol, it is preferredthat-approximately.equimol.ecular-,= pr portions, qi-a hezreactantse tiliz dr again, however, some variation is permissible as it has beenafoundrthat satisfactory. results may; be obtained hy-i utilizing. from about: 0.9; molstd; about 1.1 mols; .Of: the: alkali. metal; ar-ylatefiorl. each molecular proportion. of; the. alkyl ph'oser phcryl dichloriderutilized; The temperature: of.

this reaction maylalsobe maintained overa w ide..7o v

range during...'the;course of-the reaction. Thus," reaction temperaturesi'in. the range of, from; about -l0.to;.abQut--'+5Q C5 have. been found a, s res a is actory, r sales. H ist-abl .howhi nest e mmaturemaieta aeaiars.

annexe a apee. oil-interment; 9; Q-. o:$99.1 5:- C. Any of the alkali metal salts of a phenol be utilized in this reaction. Typical. of such salts are the' sodium; potassium and the lithiumsalts. Similarly any phenol may be utilized in this reaction. Thus, the phenoLmay be unsubtituiedlor. t. may. be. substituted. with. one. r. more of the following illustrative substitnents; halogens, such. as.clil'ciri'ne, iodine, bromine and fluorine; nitro groups; alkyl groups, such. as methyl, ethyl, propyl, isopropyl, butyl, sec.-butyl, amyl, etc; alkoxy' groups, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy etc.

his readies I ed.-. ut n; eseu lkal neme ium. at is. eta 2 e are h n 'et lka ne: medium e. mine-- tained by the addition of any of thecornmonly ed; l salflne al a T pi Q -sn a l? a ts a e; the al s'a me hydroxi s. h-.. s

esiiamehyerqr fl s otassium; hy oxide nd;

conditions. throughout the entire reaction or.-

they may be added continuouslyor intermit tently during thecour-se of the reaction so as to maintain an alkaline reactionmedium.

'I- he alkyl pheny-l phosphoric acid may beisolated orseparated; from" the reaction mixture by any. convenient method well known to those skilled; in the art, Since the acid is present i n the reaction mixture as its alkalimetal salt, it

may be separated therefrom as such, or it may be convertedi to the'fre'e; acid-andthen separated therefrom. Furthermore, if desired, it may be separated from the reactionrnixtureas the "free acidand subsequently converted; to. its

salt. In some cases, the alkali-metal alkyl aryl phosphates are insoluble in the aqueous reactionmedium. These solids can be removed from the reaction mass by filtration which efreet'sa separation 'fromanyneutral phosphate est h. may. also. be. resenthe Solid can then be. mixed. with. Water. and. the. phos.-- phoric acid derivatives liberated therefrom by acidification. If thealkalimetal salt is gelatinous and diflicult to filter asis, the mass'may be. mixed.- with an insoluble, inert material, such S nd: han; ara m rom. e aq eo mass b ltratin Th te i r, the kyl aryl" phosphoric acid can be recovered in the usual: manner. While some of the alkali metal salts of the alkylphenyl phosphoric acid; arersolids, the, alkyL aryl: phosphoric; acids which are obtained according. to the. novel; process. of this invention. vary. from..mobi1ev fluids to viscous liquids, as thealkyl: group isiincreasedfirom C6 to. C18.

The alkyl aryl, phosphoric acids. prepared in co dance-(w m no ocess Q h s-fi t tion may also be converted into metallic which have antioggidant actiyity for lubricating oils. The salts ofthe elements of group II of the periodietablearesparticularly useful;- Such salts include the cadmiurn salt; barium salt, and asis and-nel tra. ..z ne a1ts of ,al y ph nyl plleephoriea i s-l What is claimed is:

1. In a process for theconversion 01' alkyl phosphoryl dichlorides to salts of alkyl phenyl phosphoric acid, said acid having the formula 0 1-O1 O-R2 011 wherein R1 represents an alkyl radical terminating with a CH: group and containing from 6 to 18 carbon atoms and R2 represents a phenyl radical, the step comprising reacting a one molecular proportion of an alkyl phosphoryl di-- chloride with an aqueuos solution containing approximately a one molecular proportion of an alkali metal salt of a phenol, while maintaining the reaction mixture alkaline to phenol-phthalem.

2. In a process for the conversion of alkyl phosphoryl dichlorides to salts of alkyl phenyl phosphoric acid, said acid having the formula wherein R1 represents an alkyl radical terminating with a CH2 group and containing from 6 to 18 carbon atoms and R2 represents a phenyl radical, the step comprising reacting a one molecular proportion of an alkyl phosphoryl dichloride wherein the alkyl substituent is an alkyl radical terminating with a CH2 group and containing from 6 to 18 carbon atoms, with an ap proximately one molecular proportion of an al- 10 kali metal salt of a phenol in an aqueous medium while maintaining the aqueous reaction medium alkaline to phenolphthalein.

3. The process as described in claim 2 where in the alkyl phosphoryl dichloride is n-hexyl phosphoryl dichloride.

4. The process as described in claim 3 wherein the phenol is phenol.

5. The process as described in claim 2 wherein the alkyl phosphoryl dichloride is 2-ethylhexyl phosphoryl dichloride.

6. The process as described in claim 5 wherein the phenol is phenol.

7. The process as described in claim 5 wherein the phenol is cresol.

8. The process as described in claim 2 wherein the alkyl phosphoryl dichloride is n-decyl phosphoryl dichloride.

9. The process as described in claim 8 in the phenol is cresol.

10. The process as described in claim 2 wherein the alkyl phosphoryl dichloride is an octadecyl phosphoryl dichloride.

11. The process as described in claim 10 wherein the phenol is phenol.

' HARRY R. GAMRATH.

where- References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,005,619 Graves June 18, 1935 2,504,121 Gamrath Apr. 18, 1950 2,520,393 Fletcher Aug. 29, 1950 

1. IN A PROCESS FOR THE CONVERSION OF ALKYL PHOSPHORYL DICHLORIDES TO SALTS OF ALKYL PHENYL PHOSPHORIC ACID, SAID ACID HAVING THE FORMULA 